DESCRIPTION: The primary objective of this project is to produce new scientific knowledge about environmental risks for symptoms among workers in office environments. These findings will provide new understanding of how to reduce health risks for the 70% of the U.S. workforce in indoor environments, through improved design, operation, and maintenance of buildings. The project will involve analyses of the existing Building Assessment and Survey Evaluation (BASE) dataset collected by the U.S. EPA from a representative sample of U.S. office buildings, supplemented by additional data to be acquired from outside sources. The BASE dataset contains environmental measurements, building characterizations, and human questionnaire responses from 100 U.S. office buildings and 4,326 occupants. These data, the only such U.S. data available, have received little analysis and represent a unique opportunity to benefit indoor workers. The specific aims of this project are to (1) characterize the relationships between outdoor air ventilation rates and symptoms among indoor workers, using improved ventilation rate estimates, in order to support health-protective ventilation standards; (2) assess risks for irritation symptoms among indoor workers from sources of indoor chemical emissions such as surface materials; (3) assess evidence for irritation symptoms from products of indoor chemical reactions between reactive gases and organic compounds, by analyzing BASE data on symptoms and volatile organic compounds with newly obtained data on ozone concentrations and filter characteristics; (4) assess evidence for effect modification by the ventilation rate of the risk of irritant symptoms from indoor pollutant sources or indoor chemical reactions; (5) estimate the relationships between indoor thermal conditions and symptoms in indoor workers, using various metrics for temperature and humidity, in order to explore discrepancies between current building operation guidelines and research findings; (6) calculate normative distributions of symptom prevalence in U.S. office buildings to produce guidelines that assist building managers and investigators in the interpretation of symptoms reported in specific indoor work settings; and (7) combine statistical models produced in this project into comprehensive models and, based on a synthesis of overall BASE findings with other current knowledge, summarize identified risk factors and remaining research questions.